Solar energy is considered by many to be an attractive alternative to conventional energy generating techniques which utilize fossil or nuclear fuels. Solar energy is abundant, environmentally safe, renewable and freely available everywhere. For these reasons, considerable efforts and ressources have been devoted by the past to the development of highly efficient systems to convert solar energy into electrical, thermal or mechanical energy that is more convenient to use.
Generally speaking, solar conversion systems may be classified in two general categories. Systems that belong to the first category utilize some type of heat collector, exposed to the radiation from the sun and channeling a working fluid which absorbs heat and may then be used to drive a turbine/electrical generator group. In order to enhance the heat collection, the sun radiation may be focused on the working fluid channel by means of reflecting or refracting devices. Systems of this type may reach a relatively high degree of efficiency, however they require some type of expensive and complex tracking device to maintain the optical focussing system at an optimal angle with respect to the sun.
The second category of solar convertors includes various types of photocell devices which convert directly the sun radiation into electric power. These systems do not have the required efficiency for a wide spread commerical use and their applications are yet very limited.